The present invention relates to a novel high amperage electric switching or shunting apparatus. More particularly, it concerns a high amperage switching or shunting apparatus fitted with easily replaceable highly resistant sacrificial contacts and a fluid cooling system which makes it especially adaptable for use under high amperage loads in a corrosive atmosphere of the type commonly found in close proximity to electrolytic cells used in the production of chlorine and caustic soda.
Chlorine and caustic soda are most commonly produced by electrolysis of sodium chloride brine. The constructional features of this special apparatus employed for this process vary, however, such apparatus share a common feature in that they all require the usage of electric current. The vast majority of chlorine and caustic soda manufactured today is produced by a process utilizing electrolytic cells. In practice, a plurality of cells of a given type, often as many as 100 or more, are usually physically located in a confined area (called a cell room) and electrically connected in series. The resultant electrical arrangement of cells is commonly referred to as a "circuit".
From a commercial standpoint, it is desired to operate the cell circuit in a continuous and uninterrupted manner. The shut-down of the totality of cells, in a cell room, or a line or connected cells is a complex operation which is prohibitive in both time and economics. This means that when an individual cell in the circuit begins to exhibit undesirable operational characteristics it must be repaired or removed from the circuit in a minimum of elapsed time. To accomplish this, it is common practice to shunt the current from the concerned cell so as to remove it from the circuit for repair.
With low amperage electrolytic cells, i.e., those operating at about 50,000 to 60,000 amperes, it has been common practice to employ simple knife type air-cooled shunt switches for this purpose. However, the recent trend in chlorine and caustic production has seen the introduction of new cell designs which are capable of operating at extremely high amperage levels, e.g., amperages of 90,000 to 150,000 amps and higher. Unfortunately, conventional air cooled shunts and knife switches do not perform satisfactorily when used to shunt such high currents. The intensity of the current level creates a momentary arc between the movable arm of the knife switch and the stationary terminal contacting therewith prior to the opening and closing of the switch which welds, pits and otherwise deteriorates these parts so that their life expectancy is significantly decreased and the obtaining of an efficient contacting surface is no longer possible. As the stationary terminal and movable arm of such switches are made of highly conductive and rather expensive material, the replacing of these positive parts becomes expensive and time consuming.
Accordingly, it is the principle object of the present invention to provide a high amperage electrical switching apparatus which is capable of operating satisfactorily in a corrosive environment while providing an inexpensive and quick method to repair imminemt corrosion problems.